Influence of antipseudomonal agents on Pseudomonas aeruginosa colonization and acquisition of resistance in critically ill medical patients.
OBJECTIVE
To assess the role of antipseudomonal agents on Pseudomonas aeruginosa colonization and acquisition of resistance.


METHODS
Prospective cohort study.


METHODS
Two medical intensive care units.


METHODS
346 patients admitted for >or= 48 h.


METHODS
Analysis of data from an 8-month study comparing a mixing versus a cycling strategy of antibiotic use.


RESULTS
Surveillance cultures from nares, pharynx, rectum, and respiratory secretions were obtained thrice weekly. Acquisition of resistance was defined as the isolation, after 48 h of ICU stay, of an isolate resistant to a given antibiotic if culture of admission samples were either negative or positive for a susceptible isolate. Emergence of resistance refers to the conversion of a defined pulsotype from susceptible to non-susceptible. Forty-four (13%) patients acquired 52 strains of P. aeruginosa. Administration of piperacillin-tazobactam for >or= 3 days (OR 2.6, 95% CI 1.09-6.27) and use of amikacin for >or= 3 days (OR 2.6, 95% CI 1.04-6.7) were positively associated with acquisition of P. aeruginosa, whereas use of quinolones (OR 0.27, 95% CI 0.1-0.7) and antipseudomonal cephalosporins (OR 0.27, 95% CI 0.08-0.9) was protective. Exposure to quinolones and cephalosporins was not associated with the acquisition of resistance, whereas it was linked with usage of all other agents. Neither quinolones nor cephalosporins were a major determinant on the emergence of resistance to themselves, as resistance to these antibiotics developed at a similar frequency in non-exposed patients.


CONCLUSIONS
In critically ill patients, quinolones and antipseudomonal cephalosporins may prevent the acquisition of P. aeruginosa and may have a negligible influence on the acquisition and emergence of resistance.
Martínez
José A
JA
Department of Infectious Diseases, Hospital Clínic, IDIBAPS, University of Barcelona, Barcelona, Spain. jamarti@clinic.ub.es
Delgado
Esther
E
Martí
Sara
S
Marco
Francesc
F
Vila
Jordi
J
Mensa
Josep
J
Torres
Antoni
A
Codina
Carles
C
Trilla
Antoni
A
Soriano
Alex
A
Alquezar
Aitor
A
Castro
Pedro
P
Nicolás
José M
JM
D000328:Adult; D002511:Cephalosporins / Q000627:therapeutic use*; D016638:Critical Illness / Q000453:epidemiology*; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004338:Drug Combinations; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005260:Female; D005814:Genes, Viral / Q000235:genetics; D005838:Genotype; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D008297:Male; D010614:Pharynx / Q000382:microbiology; D010878:Piperacillin / Q000627:therapeutic use*; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000302:isolation & purification*; D015363:Quinolones / Q000627:therapeutic use*; D012007:Rectum / Q000382:microbiology; D020545:Respiratory Mucosa / Q000382:microbiology
D002511:Cephalosporins; D004338:Drug Combinations; D004791:Enzyme Inhibitors; D015363:Quinolones; D010878:Piperacillin